The University of Pennsylvania Health System's Department of Obstetrics and Gynecology reflects a long tradition of excellence in clinical and translational research. Investigators within the Division of Maternal-Fetal Medicine have been key participants in this tradition, particularly in their studies of genetic factors and environmental exposures that are associated with preterm birth. In this application, we provide information on the two hospitals that comprise the obstetric services at the University of Pennsylvania - the Hospital of the University of Pennsylvania (HUP) and Pennsylvania Hospital (PAH) - both of which are proposed sites of patient recruitment for the network. The specific aims of this application are: 1) to provide consultation on the design of network studies, which includes assisting the Steering Committee in study design, sample size calculations, and statistical analyses, and selecting optimal data and sample collection protocols; 2) to enroll subjects into network studies and to provide quality data for network studies; 3) to perform ultrasound studies, laboratory assays, and high-throughput genomics and proteomics assays required to complete proposed studies; and 4) to be involved in the analysis and publication of network studies. The combined delivery volume of HUP and PAH is over 9,000 per year. The MFM physicians at the two hospitals share clinical responsibilities and have a substantial track record for collaboration in various clinical studies. Importantly, the principal investigator for this application is the principal investigator of the Analytical Core for the Genomics and Proteomics Network for Preterm Birth Research and will bring significant expertise regarding study design, sample collection, and assay techniques (including high-throughput studies), to the proposed preterm birth network. The investigators propose a prospective cohort study in which prenatal ultrasound findings (cervical length, uterine artery Doppler flow), protein biomarkers (circulating angiogenic factors, proteomics techniques using labeled proteins from cells of interest), and transcriptomics assays will be correlated with clinical outcomes and placental histology findings. The hypothesis to be tested is that markers of placental dysfunction early in pregnancy will identify nulliparous women at risk of preterm birth.